If Haki is will power, then Power of Love appears to represent the strongest of wills: the will to protect loved ones.
Like Haki, love is commonly described as transcending all. Conquering all. This evidently includes the laws of physics.
Sanji has the most notorious physics-defying feat using PoL, but he wasn't the first person to use PoL
or to use it to defy the laws of physics - Garp was.
In SBS 62 Oda explicitly confirmed it was not Haki but "love" that Garp used to hurt Luffy, a rubber-man.
In hindsight, it would appear obvious Rouge could only endure her prolonged pregnancy because of PoL.
Vegapunk outright speculated Kuma managed protect Bonney because of it.
Thriller Bark also had a striking example.
I'm sure there are other instances we can speculate over, but the bottom line is that PoL is not only very much real, it's been a real part of One Piece for a very long time.
Fundamentally, I don't think PoL is Conqueror's Haki, but a lot of Conquerors have it because they have powerful wills that extend to those they love. I don't think Rouge or Kuma had CoC but the unyielding love of a parent for their child.
Sanji will likely awaken CoC and PoL will be what allows him to achieve feats with Haki others can't - like destroying lasers.